Argosy uncovers deeper upside beneath 790,000-tonne Rincon resource

Rincon Resource Reaches 790,000 Tonnes

Argosy Minerals Limited (ASX:AGY) has put a larger resource base behind its proposed Rincon lithium development in Argentina, lifting the project’s total JORC 2012 Mineral Resource Estimate to 790,000 tonnes of lithium carbonate equivalent. The estimate contains 600,000 tonnes in the Indicated category and 190,000 tonnes classified as Inferred.

“Rincon Lithium Project – View of the resource model showing the lithium grade distribution in g/m³.”

The resource is contained in an estimated 0.428 cubic kilometres of brine, with an average lithium concentration of 348 milligrams per litre. The Indicated portion carries an average concentration of 332mg/L, while the Inferred component is higher at 411mg/L. Those figures describe lithium-bearing brine in the aquifer, rather than a conventional hard-rock orebody.

Deeper Aquifer Adds Conceptual Upside

The more speculative part of the announcement sits beneath the upgraded resource. Argosy has defined an Exploration Target ranging from 390,000 to 1.03 million tonnes of lithium carbonate equivalent, based on lithium concentrations between 377mg/L and 425mg/L. The target occupies a modelled aquifer volume of 3.27 cubic kilometres and is separate from, and excluded from, the Mineral Resource Estimate.

That distinction matters. The Exploration Target is conceptual, based on extrapolation below the classified resource, and the company cautions that further exploration may not result in an additional Mineral Resource. Argosy says the basin remains open at depth, with the current three-dimensional model extending to 600 metres for modelling purposes rather than establishing a defined resource boundary.

Resource Upgrade Feeds Rincon DFS

The resource work forms part of a broader hydrogeological program intended to support production wellfield design, a JORC Ore Reserve and the Definitive Feasibility Study for a proposed 12,000-tonne-per-year Rincon operation. The update arrives after the company’s Rincon crystallisation engineering milestone, which defined the process configuration, equipment sizing and plant layout for the evaporation and crystallisation circuit.

Argosy says the updated resource will be used to prepare the wellfield design and Ore Reserve. The Competent Person’s assessment also states that pumping-test results indicate the brine could be extracted through a conventional production wellfield, while its chemistry may be suitable for conventional processing. Those are resource-level conclusions, however; the Ore Reserve, final project economics and development decision remain ahead.

Deep Drilling Becomes the Next Test

“Rincon Lithium Project – Drillhole & Tenement Location Map.”

Argosy has completed 4,459 metres across 29 brine investigation holes, with the resource estimate drawing on 215 lithium analyses from 22 drill holes and specific-yield data from 45 laboratory analyses across seven holes. The company says Atacama Water Consultants reviewed and standardised the lithological database before updating the geological and hydrogeological models.

Testing the deeper target will require surface geophysics and two to four diamond holes reaching 600 metres, alongside drainable-porosity analysis, brine sampling and borehole magnetic resonance logging. The next material question is therefore not whether Rincon has more conceptual volume on paper, but how much of that deeper aquifer can be confirmed, modelled under pumping conditions and ultimately converted into an Ore Reserve.